600 



liAYMOND riOAUL. 



iU'tion ol' till' iMiiTi'iit , llu' iKiliin' ol' tlu- contract ions and 

 relaxations of dilTiTi-nt pai-ts of the body can \>c very fU-arly 

 scHMi, and since tlicsc arc the most signiiicant features of thi> 

 animal's reactions to the electric current, they niay be iK'- 

 scribed a little more fully. These reactions for tlie three 

 cliii'f positions are shown in I'ig. 47. The essential features 

 art" contraction of tlu' anode eml of the body Avlien in line 

 with the cui'rent, and convexity on the anode side when at 

 right angles. IJesides this there seems to be some slight 

 exj)ansion at the kathode end of s]X'cimens in line with the 

 curi'ent, but this a])])earance is ne)t constant. Iveversal of the 

 current in these paralysed specimens causes contraction at 



/^^- 



+ 



Yic. 4-7. — Diagram bhowiii;;; llic contractions caused by tlie current with 

 tlic l)ody in tiic three principal pot-itions. 



the new anode imuI or bending towards the new kathode. On 

 breaking the current the contracted portions relax. 



c. Mechanism of the Iveactions. — It will be seen from 

 the figures, and the accemnt which has been given ol' tlu' 

 n>sponses to the electric current, that there is an apjiarent 

 anomaly in the lu'liaviour. The specimen contracts always 

 at the anode end of the body, 1)ut a]i])ai'ently not on the 

 anoiU' side of the body. 1 believe that the explanation foi- 

 this ap]iarent dilferenci' in behaviour is to be found in the 

 structure of tlu- animal, and in a pi'culiarity in the action oi 

 the constant current which has binm noted in another case. 

 When the animal is in line with the current the contraction 



